A plain language summary of the results from the phase 2b HERIZON-BTC-01 study of zanidatamab in participants with HER2-amplified biliary tract cancer.

WHAT IS THIS SUMMARY ABOUT?: Researchers wanted to study whether the research drug zanidatamab could help people with a type of cancer called biliary tract cancer. In some people, biliary tract cancer cells make extra copies of a gene called HER2 (also called ERBB2). This is known as being HER2-amplified. Zanidatamab is an antibody designed to destroy cancer cells that have higher-than-normal HER2 protein or gene levels. Zanidatamab is currently under research and is not yet approved for any diseases. Participants in this phase 2b clinical study had tumors that were HER2-amplified and at the advanced or metastatic stage. Participants also had cancer which had become worse after previous chemotherapy or had side effects that were too bad to continue chemotherapy. They also had to meet other requirements to be enrolled. Researchers measured the amount of HER2 protein in the tumor samples of the participants who were enrolled. There were 80 participants with tumors that were both HER2 amplified and had higher-than-normal HER2 protein amounts (considered to be 'HER2-positive'). There were 7 participants with tumors that were HER2-amplified, but had little-to-no levels of the HER2 protein (considered to be 'HER2-low'). All participants in the study were treated with zanidatamab and no other cancer treatments once every 2 weeks. WHAT ARE THE KEY TAKEAWAYS?: In the HER2-positive group, 33 of 80 (41%) participants had their tumors shrink by 30% or more of their original size. In half of these participants, their tumors did not grow for 13 months or longer. No participant in the HER2-low group had their tumors shrink by 30% or more. In total, 63 of 87 participants (72%) had at least one side effect believed to be related to zanidatamab treatment. Most side effects were mild or moderate in severity. No participant died from complications related to zanidatamab. Diarrhea was one of the more common side effects and was experienced by 32 of 87 participants (37%). Side effects related to receiving zanidatamab through the vein, such as chills, fever, or high blood pressure, were experienced by 29 of 87 participants (33%). WHAT ARE THE CONCLUSIONS REPORTED BY THE RESEARCHERS?: The results of this study support the potential for zanidatamab as a new therapy for people with HER2-positive biliary tract cancer after they had already received chemotherapy. More research is occurring to support these results.Clinical Trial Registration: NCT04466891 (HERIZON-BTC-01 study).

The HERIZON-BTC-01 study revealed zanidatamab as a potentially effective treatment for HER2-positive biliary tract cancer after standard chemotherapy fails. Read more in the lay summary by @hardingjjmd, @DrShubhamPant, and coauthors. #BiliaryTractCancer #HER2 #zanidatamab.

Zanidatamab for HER2-amplified, unresectable, locally advanced or metastatic biliary tract cancer (HERIZON-BTC-01): a multicentre, single-arm, phase 2b study.

BACKGROUND: HER2 is overexpressed or amplified in a subset of biliary tract cancer. Zanidatamab, a bispecific antibody targeting two distinct HER2 epitopes, exhibited tolerability and preliminary anti-tumour activity in HER2-expressing or HER2 (also known as ERBB2)-amplified treatment-refractory biliary tract cancer. METHODS: HERIZON-BTC-01 is a global, multicentre, single-arm, phase 2b trial of zanidatamab in patients with HER2-amplified, unresectable, locally advanced, or metastatic biliary tract cancer with disease progression on previous gemcitabine-based therapy, recruited at 32 clinical trial sites in nine countries in North America, South America, Asia, and Europe. Eligible patients were aged 18 years or older with HER2-amplified biliary tract cancer confirmed by in-situ hybridisation per central testing, at least one measurable target lesion per Response Evaluation Criteria in Solid Tumours (version 1.1), and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients were assigned into cohorts based on HER2 immunohistochemistry (IHC) score: cohort 1 (IHC 2+ or 3+; HER2-positive) and cohort 2 (IHC 0 or 1+). Patients received zanidatamab 20 mg/kg intravenously every 2 weeks. The primary endpoint was confirmed objective response rate in cohort 1 as assessed by independent central review. Anti-tumour activity and safety were assessed in all participants who received any dose of zanidatamab. This trial is registered with ClinicalTrials.gov, NCT04466891, is ongoing, and is closed to recruitment. FINDINGS: Between Sept 15, 2020, and March 16, 2022, 87 patients were enrolled in HERIZON-BTC-01: 80 in cohort 1 (45 [56%] were female and 35 [44%] were male; 52 [65%] were Asian; median age was 64 years [IQR 58-70]) and seven in cohort 2 (five [71%] were male and two [29%] were female; five [71%] were Asian; median age was 62 years [IQR 58-77]). At the time of the data cutoff (Oct 10, 2022), 18 (21%) patients (17 in cohort 1 and one in cohort 2) were continuing to receive zanidatamab; 69 (79%) discontinued treatment (radiographic progression in 64 [74%] patients). The median duration of follow-up was 12·4 months (IQR 9·4-17·2). Confirmed objective responses by independent central review were observed in 33 patients in cohort 1 (41·3% [95% CI 30·4-52·8]). 16 (18%) patients had grade 3 treatment-related adverse events; the most common were diarrhoea (four [5%] patients) and decreased ejection fraction (three [3%] patients). There were no grade 4 treatment-related adverse events and no treatment-related deaths. INTERPRETATION: Zanidatamab demonstrated meaningful clinical benefit with a manageable safety profile in patients with treatment-refractory, HER2-positive biliary tract cancer. These results support the potential of zanidatamab as a future treatment option in HER2-positive biliary tract cancer. FUNDING: Zymeworks, Jazz, and BeiGene.

ILUSTRO: Phase II Multicohort Trial of Zolbetuximab in Patients with Advanced or Metastatic Claudin 18.2-Positive Gastric or Gastroesophageal Junction Adenocarcinoma.

PURPOSE: Zolbetuximab, an IgG1 monoclonal antibody, binds to claudin 18.2 (CLDN18.2) and mediates tumor cell death through antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. We sought to examine zolbetuximab combinations in CLDN18.2-positive HER2-negative gastric/gastroesophageal junction (G/GEJ) adenocarcinoma. PATIENTS AND METHODS: This phase II study assessed efficacy and safety of zolbetuximab, alone or with modified FOLFOX6 (mFOLFOX6) or pembrolizumab, in CLDN18.2-positive advanced/metastatic G/GEJ adenocarcinoma. Patients received zolbetuximab as monotherapy in third/later-line (Cohort 1A, n = 30), with mFOLFOX6 in first-line (Cohort 2, n = 21), or with pembrolizumab in third/later-line (Cohort 3A, n = 3) treatment. The primary endpoint for Cohort 1A was objective response rate (ORR). Key secondary endpoints were ORR (Cohorts 2 and 3A), overall survival (OS; Cohort 1A), and progression-free survival (PFS) and safety (all cohorts). RESULTS: ORR was 0% in Cohorts 1A and 3A, and 71.4% [95% confidence interval (CI), 47.82-88.72] in Cohort 2. Median PFS was 1.54 months (95% CI, 1.31-2.56) in Cohort 1A, 2.96 months (95% CI, 1.48-4.44) in Cohort 3A, and 17.8 months (95% CI, 8.05-25.69) in Cohort 2. Median OS in Cohort 1A was 5.62 months (95% CI, 2.27-11.53). Gastrointestinal adverse events occurred across cohorts [nausea, 63%-90% (grade ≥ 3, 4.8%-6.7%) and vomiting, 33%-67% (grade ≥ 3, 6.7%-9.5%)]. CONCLUSIONS: Zolbetuximab plus mFOLFOX6 demonstrated promising efficacy in previously untreated patients with CLDN18.2-positive G/GEJ adenocarcinoma. These data support the first-line development of zolbetuximab in patients whose tumors are CLDN18.2-positive. Across cohorts, zolbetuximab treatment was tolerable with no new safety signals.

Randomized, Double-Blind, Placebo-Controlled Phase III Study of Paclitaxel ± Napabucasin in Pretreated Advanced Gastric or Gastroesophageal Junction Adenocarcinoma.

PURPOSE: To compare napabucasin (generator of reactive oxygen species) plus paclitaxel with paclitaxel only in patients with second-line advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma. EXPERIMENTAL DESIGN: In the double-blind, phase III BRIGHTER study (NCT02178956), patients were randomized (1:1) to napabucasin (480 mg orally twice daily) plus paclitaxel (80 mg/m2 i.v. weekly for 3 of 4 weeks) or placebo plus paclitaxel. The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and safety. RESULTS: Overall, 714 patients were randomized (napabucasin plus paclitaxel, n = 357; placebo plus paclitaxel, n = 357). 72.1% were male, 74.6% had gastric adenocarcinoma, and 46.2% had peritoneal metastases. The study was unblinded following an interim analysis at 380 deaths. The final efficacy analysis was performed on 565 deaths (median follow-up, 6.8 months). No significant differences were observed between napabucasin plus paclitaxel and placebo plus paclitaxel for OS (6.93 vs. 7.36 months), PFS (3.55 vs. 3.68 months), ORR (16% vs. 18%), or DCR (55% vs. 58%). Grade ≥3 adverse events occurred in 69.5% and 59.7% of patients administered napabucasin plus paclitaxel and placebo plus paclitaxel, respectively, with grade ≥3 diarrhea reported in 16.2% and 1.4%, respectively. CONCLUSIONS: Adding napabucasin to paclitaxel did not improve survival in patients with pretreated advanced gastric or GEJ adenocarcinoma. Consistent with previous reports, the safety profile of napabucasin was driven by manageable gastrointestinal events; grade ≥3 diarrhea occurred at a higher frequency with napabucasin plus paclitaxel versus placebo plus paclitaxel.